node-paytmpg/app/controllers/checksum/checksum.js

Payment Gateway Integration using NodeJS

"use strict";

var crypt = require('./crypt');
var util = require('util');
var crypto = require('crypto');
const PaytmChecksum = require('./PaytmChecksum.js');

//mandatory flag: when it set, only mandatory parameters are added to checksum

function paramsToString(params, mandatoryflag) {
  var data = '';
  var tempKeys = Object.keys(params);
  tempKeys.sort();
  tempKeys.forEach(function (key) {
    if (!params[key]) {
      return
    }
    try {
      var n = params[key].includes("REFUND");
      var m = params[key].includes("|");
      if (n == true) {
        params[key] = "";
      }
      if (m == true) {
        params[key] = "";
      }
    } catch (e) {
      params[key] = "";
      console.log(e)
    }


    if (key !== 'CHECKSUMHASH') {
      if (params[key] === 'null') params[key] = '';
      if (!mandatoryflag || mandatoryParams.indexOf(key) !== -1) {
        data += (params[key] + '|');
      }
    }
  });
  return data;
}


function genchecksum(params, key, cb) {
  let checksumPromise = PaytmChecksum.generateSignature(params, key).then(checksum => {
    cb(undefined, checksum)
  })
  return checksumPromise;
  var data = paramsToString(params);
  crypt.gen_salt(4, function (err, salt) {
    var sha256 = crypto.createHash('sha256').update(data + salt).digest('hex');
    var check_sum = sha256 + salt;
    var encrypted = crypt.encrypt(check_sum, key);
    cb(undefined, encrypted);
  });
}
function genchecksumbystring(params, key, cb) {

  crypt.gen_salt(4, function (err, salt) {
    var sha256 = crypto.createHash('sha256').update(params + '|' + salt).digest('hex');
    var check_sum = sha256 + salt;
    var encrypted = crypt.encrypt(check_sum, key);

    var CHECKSUMHASH = encodeURIComponent(encrypted);
    CHECKSUMHASH = encrypted;
    cb(undefined, CHECKSUMHASH);
  });
}

function verifychecksum(params, key, checksumhash) {
  return PaytmChecksum.verifySignature(params, key, checksumhash)
  var data = paramsToString(params, false);

  //TODO: after PG fix on thier side remove below two lines
  if (typeof checksumhash !== "undefined") {
    checksumhash = checksumhash.replace('\n', '');
    checksumhash = checksumhash.replace('\r', '');
    var temp = decodeURIComponent(checksumhash);
    var checksum = crypt.decrypt(temp, key);
    var salt = checksum.substr(checksum.length - 4);
    var sha256 = checksum.substr(0, checksum.length - 4);
    var hash = crypto.createHash('sha256').update(data + salt).digest('hex');
    if (hash === sha256) {
      return true;
    } else {
      util.log("checksum is wrong");
      return false;
    }
  } else {
    util.log("checksum not found");
    return false;
  }
}

function verifychecksumbystring(params, key, checksumhash) {

  var checksum = crypt.decrypt(checksumhash, key);
  var salt = checksum.substr(checksum.length - 4);
  var sha256 = checksum.substr(0, checksum.length - 4);
  var hash = crypto.createHash('sha256').update(params + '|' + salt).digest('hex');
  if (hash === sha256) {
    return true;
  } else {
    util.log("checksum is wrong");
    return false;
  }
}

function genchecksumforrefund(params, key, cb) {
  var data = paramsToStringrefund(params);
  crypt.gen_salt(4, function (err, salt) {
    var sha256 = crypto.createHash('sha256').update(data + salt).digest('hex');
    var check_sum = sha256 + salt;
    var encrypted = crypt.encrypt(check_sum, key);
    params.CHECKSUM = encodeURIComponent(encrypted);
    cb(undefined, params);
  });
}

function paramsToStringrefund(params, mandatoryflag) {
  var data = '';
  var tempKeys = Object.keys(params);
  tempKeys.sort();
  tempKeys.forEach(function (key) {
    var m = params[key].includes("|");
    if (m == true) {
      params[key] = "";
    }
    if (key !== 'CHECKSUMHASH') {
      if (params[key] === 'null') params[key] = '';
      if (!mandatoryflag || mandatoryParams.indexOf(key) !== -1) {
        data += (params[key] + '|');
      }
    }
  });
  return data;
}

function checkRazorSignature(razorpayOrderId, razorpayPaymentId, secret, razorpay_signature) {
  const hmac = crypto.createHmac('sha256', secret);

  hmac.update(razorpayOrderId + "|" + razorpayPaymentId);
  let generatedSignature = hmac.digest('hex');

  let isSignatureValid = generatedSignature == razorpay_signature;
  return isSignatureValid
}

module.exports.genchecksum = genchecksum;
module.exports.verifychecksum = verifychecksum;
module.exports.verifychecksumbystring = verifychecksumbystring;
module.exports.genchecksumbystring = genchecksumbystring;
module.exports.genchecksumforrefund = genchecksumforrefund;
module.exports.checkRazorSignature = checkRazorSignature;